EconStor Collection:
http://hdl.handle.net/10419/24
2016-09-26T05:31:35ZA hierarchical model of tail dependent asset returns for assessing portfolio credit risk
http://hdl.handle.net/10419/57784
Title: A hierarchical model of tail dependent asset returns for assessing portfolio credit risk
Authors: Puzanova, Natalia
Abstract: This paper introduces a multivariate pure-jump Lévy process which allows for skewness and excess kurtosis of single asset returns and for asymptotic tail dependence in the multivariate setting. It is termed Variance Compound Gamma (VCG). The novelty of my approach is that, by applying a two-stage stochastic time change to Brownian motions, I derive a hierarchical structure with different properties of inter- and intra-sector dependence. I investigate the properties of the implied static copula families and come to the conclusion that they are ordered with respect to their parameters and that the lower-tail dependence of the intra-sector copula is increasing in the absolute values of skewness parameters. Furthermore, I show that the joint characteristic function of the VCG asset returns can be explicitly given as a nested Archimedean copula of their marginal characteristic functions. Applied to credit portfolio modelling, the framework introduced results in a more conservative tail risk assessment than a Gaussian framework with the same linear correlation structure, as I show in a simulation study. To foster the simulation efficiency, I provide an Importance Sampling algorithm for the VCG portfolio setting.2011-01-01T00:00:00ZContagion at the interbank market with stochastic LGD
http://hdl.handle.net/10419/45176
Title: Contagion at the interbank market with stochastic LGD
Authors: Memmel, Christoph; Sachs, Angelika; Stein, Ingrid
Abstract: This paper investigates contagion at the German interbank market under the assumption of a stochastic loss given default (LGD). We combine a unique data set about the LGD of interbank loans with data about interbank exposures. We find that the frequency distribution of the LGD is u-shaped. Under the assumption of a stochastic LGD, simulation results show a more fragile banking system than under the assumption of a constant LGD. There are three types of banks concerning their tendency to trigger contagion: banks with strongly varying impact, banks whose impact is relatively constant, and banks with no direct impact.2011-01-01T00:00:00ZThe importance of qualitative risk assessment in banking supervision before and during the crisis
http://hdl.handle.net/10419/48860
Title: The importance of qualitative risk assessment in banking supervision before and during the crisis
Authors: Kick, Thomas; Pfingsten, Andreas
Abstract: Banking supervision requires regular inspection and assessment of financial institutions. In Germany this task is carried out by the central bank ('Deutsche Bundesbank, BBK') in cooperation with the Federal Financial Supervisory Authority ('Bundesanstalt für Finanzdienstleistungsaufsicht, BaFin'). In accordance with the Basel II approach, quantitative and qualitative information is used. It is still an open question whether supervisors provide information, based on on-site inspections, which is not known from the numbers already, or simply duplicate the quantitative information, or even overrule it by their impressions gained through visits. In our analysis we use a unique dataset on financial institutions' risk profiles, i.e. the banking supervisors' risk assessment. Methodologically, we apply a partial proportional odds model to explain the supervisor's ordinal grading by a purely quantitative CAMEL covariate vector, which is standard in many bank rating models, and we also include the bank inspector's qualitative risk assessment into the model. We find that not only the quantitative CAMEL vector is clearly important for the final supervisory risk assessment; it is, indeed, also qualitative information on a bank's internal governance, ICAAP, interest rate risk, and other qualitative risk components that plays an equally important role. Moreover, we find evidence that supervisors have become more conservative in their final judgement at the beginning of the financial crisis, i.e. the supervisory assessment seems to be more forward-looking than the mere numbers. This result underpins the importance of bank-individual on-site risk assessments.2011-01-01T00:00:00ZContagion in the interbank market and its determinants
http://hdl.handle.net/10419/57782
Title: Contagion in the interbank market and its determinants
Authors: Memmel, Christoph; Sachs, Angelika
Abstract: Carrying out interbank contagion simulations for the German banking sector for the period from the first quarter of 2008 to the second quarter of 2011, we obtain the following results: (i) The system becomes less vulnerable to direct interbank contagion over time. (ii) The loss distribution for each point in time can be condensed into one indicator, the expected number of failures, without much loss of information. (iii) Important determinants of this indicator are the banks' capital, their interbank lending in the system, the loss given default and how equal banks spread their claims among other banks.2011-01-01T00:00:00Z